This invention relates to an electronic timepiece, and more particularly to a high precision electronic timepiece in which variations of the frequency of a quartz oscillator are compensated by adjustably changing the dividing ratio of a dividing circuit to produce a predetermined time signal.
The quartz oscillators which have been conventionally produced do not always generate pulses at constant frequency. The quartz oscillator is typically trimmed by means of a laser in order to remove and to adjust for any variation of the frequency thereof. However, there is a disadvantage in that such a trimming operation is difficult and expensive.
Then, it has been proposed that the variation of the frequency of the quartz oscillator may be adjusted by making it possible to adjustably change the dividing ratio of the dividing circuit which is connected to the quartz oscillator circuit in consideration of the variation of the frequency thereof.
In this case, a time signal is produced when the count value of a counter which counts output pulses of the quartz oscillator is coincident to the memory value of a memory circuit counting and memorizing the output pulses of the quartz oscillator which are generated in a fundamental time determined by utilizing a high precision external or outside time standard reference signal.
However, in the above-mentioned case, disadvantages still remain in that the high precision time standard reference signal from the outside is needed together with a coincidence circuit which includes many terminals, and therefore is difficult to miniaturize and manufacture such circuits in integrated form.